Liquid sensors of a type employing metal electrodes are used widely in many industrial, commercial, and domestic applications. Typically, in such a sensor, metal electrodes are spaced from each other by some porous, notched, or slotted element permitting electrically conductive liquids, such as water, to cause a short circuit between such electrodes. Some known sensors of the type noted above employ short, rigid electrodes, and others employ elongate, flexible electrodes.
Liquid sensors of the type noted above are exemplified in numerous prior patents including Jore et al. U.S. Pat. No. 3,098,116, Caprillo et al. U.S. Pat. No. 3,732,556, Gustafson U.S. Pat. No. 3,824,460, Kullberg U.S. Pat. No. No. 4,136,823, Westphal et al. U.S. Pat. No. 4,319,232, Braley U.S. Pat. No. 4,418,712, Akiba U.S. Pat. No. 4,843,305, Bosich U.S. Pat. No. 4,922,232, Hofberg U.S. Pat. No. 5,008,650, Lofgren U.S. Pat. No. 5,084,679, Richards U.S. Pat. No. 5,109,069, and Bailey U.S. Pat. No. 5,410,255. Liquid sensors of related interest are exemplified in Shuman U.S. Pat. No. 3,778,570, Krebs U.S. Pat. No. 5,188,143 and Furr U.S. Pat. No. 5,315,291.
Generally, in a liquid sensor of the type noted above, such electrodes are made from single or multiple strands of copper. Although copper electrodes may be generally satisfactory for many applications, copper tends to corrode under common conditions, as when exposed to high humidity or other moisture or when subjected to galvanic corrosion due to a dissimilar metal. Because of its tendency to corrode, copper is unsuited for some applications. It is known for such copper electrodes to be gold-plated to inhibit their corrosion.